The intensive industrial processes used to produce ultra-processed foods destroy the natural structure of food ingredients and strip many beneficial nutrients such as fiber, vitamins, minerals, and phytochemicals.
Many of us are well aware that ultra-processed foods are bad for our health. But it is not clear if this is simply because these foods are of poor nutritional value. Now, two new studies have shown that poor nutrition may not be enough to explain the health risks. This indicates that other factors may be needed to fully explain its health risks.
The role of inflammation
The first study, which took more than 20,000 healthy Italian adults, found that participants who ate the most ultra-processed foods had the highest risk of early death from any cause. The second study, which included more than 50,000 male health professionals in the United States, found that higher consumption of ultra-processed foods is associated with an increased risk of colon cancer.
What is most interesting about these studies is that the health risks from a diet rich in ultra-processed foods remained even after they were responsible for the poor nutritional quality of their diets. This suggests that other factors contribute to the damage caused by ultra-processed foods.
It also means that getting the right nutrients elsewhere in the diet may not be enough to eliminate disease risk from consuming ultra-processed foods. Likewise, the food industry’s attempts to improve the nutritional value of ultra-processed foods by adding a few vitamins may be a side step to a more fundamental problem with these foods.
So what factors might explain why ultra-processed foods are bad for our health?
The Italian study found that markers of inflammation — such as a high white blood cell count — were higher in the groups that ate the most processed foods. Our bodies may trigger an inflammatory response for any number of reasons – for example, if we catch a cold or are injured. The body responds by sending signals to our immune cells (such as white blood cells) to attack any invading pathogens (such as bacteria or viruses).
Our inflammatory response usually resolves very quickly, but some people may develop chronic inflammation throughout the body. This can cause tissue damage, and it also contributes to many chronic diseases – such as cancer and cardiovascular disease.
Several studies have found that poor diets can increase inflammation in the body, and that this is linked to an increased risk of chronic disease. Given the appearance of inflammatory markers in the Italian study participants who ate the most over-processed foods, this may suggest that inflammation may contribute to an increased risk of over-processed foods. Some food additives common in ultra-processed foods (such as emulsifiers and artificial sweeteners) also increase inflammation in the gut by causing changes in the gut microbiome.
Some researchers hypothesize that ultra-processed foods increase inflammation because the body recognizes them as foreign — like invading bacteria. So the body mounts an inflammatory response, which it calls “junk food fever.” This increases inflammation throughout the body as a result.
Although the American Colon Cancer Study did not determine whether inflammation was increased in men who consumed the most over-processed foods, inflammation is closely associated with an increased risk of colon cancer.
Research shows that other mechanisms — such as impaired kidney function and toxins in the pack — may also explain why ultra-processed foods cause so many serious health problems.
Since inflammatory responses are solid in our bodies, the best way to prevent this from happening is to not eat ultra-processed foods at all. Some plant-based diets rich in natural, unprocessed foods (such as the Mediterranean diet) have also been shown to be anti-inflammatory. This may also explain why plant-based diets devoid of ultra-processed foods can help ward off chronic disease. It is currently unknown to what extent an anti-inflammatory diet can help counter the effects of ultra-processed foods.
Simply cutting back on ultra-processed foods can be a challenge. Ultra-processed foods are designed to be overly palatable — and combined with persuasive marketing, it can make resisting them a formidable challenge for some people.
These foods are also not labeled as such on food packaging. The best way to get to know them is to look at their ingredients. Usually things like emulsifiers, thickeners, protein isolates, and other industrial products are a sign that it’s a highly processed food. But preparing meals from scratch using natural foods is the best way to avoid the harms of ultra-processed foods.
Richard Hoffman is an associate lecturer in nutritional biochemistry at the University of Hertfordshire.